Fill in the Blank. Explain Your Reasoning

Multiple Choice

Fill in the blank. Explain your reasoning.
-If the population of Country X is 28% less than the population of Country Y, then Country X's population is____% of Country Y's population.

A) 28%; Country X's population is 28% of Country Y's population.
B) 72%; Country X's population is 100% of Country Y's population minus 28% of Country Y's population.
C) -28%; Country X's population is -28% of Country Y's population.
D) 128%; Country X's population is 100% of Country Y's population plus another 28%.